Welcome the Flood-Waters

Keep the water out. For decades, that’s how cities have tried to prevent flood damage. In Venice, at least $7 billion is being spent on sea gates. Post-Katrina New Orleans is building levees and flood walls. And most recently, all of that has been proposed to ensure that the U.S. East Coast can weather its next Sandy-size superstorm.

But as sea levels rise and storms get fiercer and more frequent, those costly, superficial barriers will not be enough — or so say a growing number of urban planners and engineers. Already, experts are predicting the Venice sea gates could cripple the city’s ecosystem if they’re closed for long periods of time. And in cities like New Orleans, shelling out to construct water barriers prevents the government from investing in other vital projects such as new parks and roads.

With that in mind, some of the world’s biggest metropolises are starting to embrace “accommodation” architecture: building multipurpose structures to let water in during surges. For some structures, the proposed design tweaks are minimal: moving heat and electrical controls from the basement to the attic, for example, or ensuring that elevators start at the second floor. The more ambitious projects, however, do a lot more than manage floods. In Rotterdam, low-lying playgrounds made with water-resistant materials double as storage basins when heavy rainfall hits. In Singapore, new parkland helps funnel water through a purification system. And in New York City, so-called green roofs will absorb rainwater and recycle it to nourish grass, trees and other plants.

Of course, these projects are complicated and expensive (New York’s Green Infrastructure Plan carries a $2.9 billion price tag) and will likely need to supplement — not replace — existing water barriers. We know the water is coming. The sooner we accept that we can’t keep all of it out, the safer we will be.